1. Field of the Invention
This invention relates to pneumatic tires, and more particularly to reinforcement belts for heavy duty pneumatic tires.
2. Prior Art
It is known in the industry to construct heavy duty pneumatic tires including an annular reinforcement belt or breaker about the crown periphery of the tire between the tread and the carcass. In such constructions the reinforcement belt has a substantially planar or flat cross-sectional configuration owing to the particular cross-sectional configuration of the tire carcass in which the carcass between the point of maximum width in the sidewall and the tread is bent noticeably. The tire therefore has a relatively low elevation so that the radial height of the tire above the rim on which it is mounted is less than that of conventional heavy duty pneumatic tires.
One reinforcement belt construction for such a heavy duty pneumatic tire is described in U.S. Pat. No. 3,757,844 and includes a folded ply enclosing an unfolded ply with another unfolded ply positioned between the folds. The reinforcement elements in each ply are steel. Another reinforcement belt construction suggesting the utilization of all steel plies is disclosed in U.S. Pat. No. 3,500,890.
As noted hereinabove, heavy duty pneumatic tires have a generally flat cross-sectional configuration. This configuration must be maintained not only while the tire is inflated and in operation but during the manufacturing process as well. Known manufacturing procedures impart the flat configuration to the carcass before the reinforcement belt is placed thereon. It would be a less complex process to first position the reinforcement belt on the carcass and then shape the carcass to the desired flat configuration. Such a reinforcement belt would necessarily contain a fettering or clamping ply which would retain the reinforcement belt on the carcass and shape the carcass into the flat cross-sectional configuration. Fettering or clamping ply constructions are disclosed in U.S. Pat. Nos. 3,786,851, 3,850,219, 3,949,797 and German Patent No. 2,431,977.
The reinforcement belts which have heretofore been designed do not guarantee that when used on a standard radial carcass, the carcass will assume the desired flat cross-sectional configuration due, solely, to the effects of the reinforcement belt.
It is towards elimination of these and other problems in the prior art that the present invention is directed.